Mechanical accumulators for roll crushers

ABSTRACT

A mechanical accumulator, which maintains the spacing of the rolls in a roll crusher and absorbs overloads, utilizes a cylinder of nylon as a kind of &#39;&#39;&#39;&#39;spring&#39;&#39;&#39;&#39; of very high rate which compresses to absorb limited overloads, protection against further overloads being provided by typical shear washers.

limited States Patent 1191 Lillig et a1. Nov. 5, 1974 MECHANICAL ACCUMULATORS FOR 3,166,257 1/1965 Pick et a1. 241 231 x ROLL CRUSHERS 3,315,902 4/1967 Pollitz 241/231 3,424,448 1/1969 Chak Ma 188/268 X [75] Inventors: Floyd A. Lllllg; Edward 0. 3,478,972 11/1969 Hansen 241/230 Spangler, both of Cedar Rapids,

Iowa Primary Examiner-Granville Y. Custer, Jr. [73] Assignee: Iowa Manufacturing Company, Assistant ExaminerHoward N. Goldberg Cedar Rapids, lowa Attorney, Agent, or Firm-Haven E. Simmons; James 22 Filed: Apr. 21,.1972 Nemme 21 Appl. No.2 245,958

[57] ABSTRACT Cl 241/231 A mechanical accumulator, which maintains the spac- B026 13030 23/04 ing of the rolls in a roll crusher and absorbs overloads, Field of Search utilizes a cylinder of nylon as a kind of spring of 188/268 very high rate which compresses to absorb limited overloads, protection'against further overloads being [56] References Cited provided by typical shear washers.

UNITED STATES PATENTS l D 2,273,772 2 1942 Pollitz 241 32 8 C 5 5" SREEIZGF 3 PATENTEU NOV 5 law:

DIAMETER IN !NCHES PATENTED NOV 5 I97 LENGTH lN INCHES FIG LOAD (x 1,000) m ouwos 225,000 LBS LOAD 0 LBS LOAD LENGATHMIN INCHES FIG 5 MECHANICAL ACCUMULATORS FOR ROLL CRUSHERS BACKGROUND OF THE INVENTION US. Pat. No. 3,315,902 of Apr. 25, 1967 to Pollitz discloses gas hydraulic spring assemblies for roll crushers. In it is pointed out that roll crushers have typically theretofore used coil spring assemblies to maintain spacing of the rolls and to absorb overloads. These require the turning up of several large screw nuts in order to load the springs the proper amount, a rather lengthy and laborious process. Not only that, but before any adjustment of the spacing of the rolls can be made, which is usually accomplished by the insertion or removal of shims, the nuts must be backed off entirely before the adjustment can be made and then retightened, all adding to the labor and time required. In place of coil springs the patent referred to substitutes severalselfcontained hydraulic spring assemblies, each having a fixed overall length and compressible by means of a piston in a cylinder working against gas of a predetermined pressure therein in order to accommodate overloads. I

The hydraulic spring assemblies are disposed between the movable roll and the crusher frame, the closed ends of the cylinders bearing against the journals of the movable 'roll while the exposed ends of the pistons extending fromthe other end of the cylinders are tightly engaged by snub bolts threaded into the frame.

This results, as the Pollitz patent points out, in the necessary loading of the movable roll being instantly available as soon as the snub bolts are turned up tight. The bolts need not be tightened to compress the gas in the cylinder in order to maintain the movable roll or to absorb overloads the predetermined pressure of the gas in the cylinders does that but only enough 'to capture the spring assemblies tightly between the movable journals and the frame. Hence, not only can the crusher initially be set up much more easily and quickly but subsequent adjustments of the spacing of the rolls can be made far more readily as well, both simply by turning the snub bolts in or out, a quick and easy operation. Loading of the movable roll, and thus the overload protection provided, is varied of course by adjusting the gas pressure in the hydraulic springs.

The gas hydraulic spring assemblies of the Pollitz patent have proved very successful in practice. They do, however, require a source of gas, usually nitrogen, under pressure in the field in order to adjust the gas pressure in the cylinders. They also can leak under certain circumstances and they are relatively expensive. The chief object of the present invention is, therefore, to provide a version of the gas hydraulic spring assemblies which embodies most of the features of the latter but which is simpler and less costly.

SUMMARY OF THE INVENTION ln overall configuration, the mechanical accumulamovable roll. A snub bolt is threaded into the frame and works against a solid nylon cylinder or spring." The latter is in effect tightly captured between the closed end of the cylindrical housing and the snub bolt,

the nylon spring being of a somewhat lesser diameter than the interior of the cylindrical housing. When the snub bolts of both accumulators are turned up to provide what may be called the working or crushing load upon the movable roll, the nylon springs of both accumulators are compressed a small amount. Beyond that they fluctuate in length over a small range during normal crushing operation but if uncrushable material of a certain range of sizes enters the rolls, forcing the rolls apart, the springs compress still further to absorbthe overload until the uncrushable material has passed, whereupon the nylon springs back and returns the movable roll to its original setting, the nylon thus acting in effect like a spring of very high rate. If the uncrushable material is so large that the nylon springs are compressed to a still further point, the resulting further increased load fractures shear washers incorporated in the snub bolts and releases the movable roll in order to protect the crusher from damage. To put it another'way, the springs fluctuate in length slightly during ordinary crushing loads and then are permitted to compress over a certain further range to absorb a correlative range of overloads, but if compressed beyond the latter range the correlative additional overload is designed to fracture the shear washers.

Accordingly, the mechanical accumulators of the present invention provide many of the advantages of the gas hydraulic springs of the Pollitz patent, and yet obviously are simpler and cheaper insofar as their manufacture are concerned. Noleakage problems are involved, nor are precise tolerances or fit of the parts necessary.'Being self-contained units they can also be readily replaced or substituted. Primarily, onlyin the event the uncrushable material is so large as to cause the shear washers to fracture are the accumulators of the present invention at a comparable disadvantage, the gas hydraulic springs being able to accommodate the-larger uncrushable material without need for shear washers or other protective overload devices. Even so,

1 replacement of those washers is far easier and less time other crushers substantial amounts before sufficient pressure is available. For the same reason, adjustment of the spacing of the rolls is also easily and quickly done. Other and further features and advantages of the present inventionwill become apparent from the drawings and the more detailed description which follow.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial side elevation of a roll crusher incorporating a mechanical accumulator according to the present invention, certain portions of the latter being shown in section to illustrate its details.

FIG. 2 is a partial end elevation taken from the right hand side of FIG. 1.

FIG. 3 is an exploded isometric view of the accumulator itself.

FIGS. 4 and 5 are graphs, the former of spring length plotted against load, and the latter of spring diameter and length plotted against load.

DESCRIPTION OF THE PREFERRED EMBODIMENT Inasmuch as the basic structure and operation of roll crushers are well known in the art, no extensive description or illustration of them is necessary in order for the present invention to be adequately set forth. Hence, this description and the drawings are confined primarily to the details of the accumulators and only incidently to the roll crusher itself.

As shown in the drawings, the roll crusher is provided with a basic frame including a pair of spaced, horizontal I-beams (only one being shown) suitably interconnected and braced. To the top face of each beam 10 is welded a lower slide bar 11, a plate 12 therebetween serving to stiffen both. An upper slide bar 13, partially supported on frame posts 14 (only one being shown) is disposed above each lower slide bar 11 parallel thereto, the two upper bars 13 being interconnected by cross bars 15, with the latter, the upper bars 13 and the frame posts 14 being held together and to the beams 10 by bolts 16. Between the two pairs of lower and upper slide bars 11 and 13 are rigidly secured two bearing blocks 17 (only one being shown) in which the fixed crushing roll 18 is journaled at 19. Laterally spaced from the fixed bearing blocks 17, by means of fixed spacer blocks 20 (only one being shown) secured by bolts 21 to the beams 10 and upper slide bars 13, are the movable bearing blocks 22 (only one being shown) in which the movable roll 23 is journaled at 24. The movable bearing blocks 22 are slidable along and between the lower and upper slide bars 11 and 13 to adjust the spacing between the rolls 18 and 23, and are retained therebetween by means of ears 25 at the respective corners of the blocks 22 which overlap the vertical faces of the slide bars 11 and 13. The desired spacing of the rolls 18 and 23 is achieved by means of two sets of shim packs for each bearing block 22, the first set 26a being disposed between one of the spacer blocks 20 and its associated bearing block 22 and the second set 26b between the latter and one of the mechanical accumulators, generally indicated at 30, of the present invention. It is understood of course, that two such accumulators 30, one for each bearing block 22, are employed though only one is illustrated and will now be described.

Each accumulator 30 includes a pair of spaced plates 31 and 32 disposed vertically between the slide bars 11 and 23 and somewhat wider than both. Between the opposed faces of the plates 31 and 32 is welded a cylindrical housing 33 whose axis coincides with the line of thrust from the frame post 14 through and perpendicular to the axis of the rolls 18 and 23. One end of the housing 33 is closed by the plate 31 but the other end is open, extending through and somewhat beyond the other side of the plate 32. The two plates 31 and 32 and the housing 33 are slidable as a unit between the frame post 14 and the shim pack 26b, the other face of the plate 31 bearing against the face of the latter. The accumulator 30 is maintained between the bars 11 and 13 by means of cars 34, bolted to the respective overlapping corners of the plates 31 and 32, which slidably engage the vertical faces of the slide bars 11 and 13. Within the housing 33 against the plate 31 is disposed first an annular spacer 35, then a back up disc 36, next the spring 37, a solid cylinder of nylon, a second back up disc 38, and finally the shank of a cylindrical shear head 39, all abutting each other. The shear head 39 is axially bored from its outer, collared end to provide a relief well 40 and then counterbored to provide a shoulder 41 against which bears a split shear washer 42. The latter encompasses a groove 43 about the inner end of a snub bolt 44 threaded through the frame post 14 and lockable by means of a set screw 45 having a nylon plug 46 ahead of it to avoid damage to the threads of the snub bolt 44. Hence, as will be apparent, any force tending to separate the rolls 18 and 23 will be transmitted by the movable bearing block 22 through the shim pack 26b to the plate 31 and then to the plate 32 through the housing 33. That force is resisted by the spacer 35, the back up discs 36 and 38 and the nylon spring 37 therebetween acting against the shear head 39, shear washer 42 and snub bolt 44 anchored in the frame post 14. In order to re-enforce the latter against the forces imposed by the snub bolt 44, suitable abutment blocks 47 are welded in the corners between the outer ends of the slide bars 11 and 13 and the post 14. 1

Each spring 37 is of sufficient size and rigidity, that is to say, its spring rate is sufficiently high, so that up to a predetermined crushing load the two springs 37 together substantially maintain the predetermined spacing of the rolls l8 and 23, but if that load is increased beyond a certain point, as by the passage of uncrushable material, the springs 37 will compress axially and expand diametrically, thus permitting the bearing blocks 22, shim packs 26b, plates 31 and 32 and housing 33 to retreat on the slide bars 11 and 13 relative to the shear head 39 until the uncrushable material has passed, whereupon the nylon will spring back to restore the spacing of the rolls 18 and 23. This may be illustrated in more detail by considering a working example of the springs" 37, each employing a cylinder substantially 6 inches in length and 5 inches in diameter formed of Type MCl nylon, whose relationship of length versus load is shown by FIG. 4. Other sizes are used, as pointed out hereafter, in connection with different sized crushers, but FIG. 4 is typical.

The snub bolts 44 are turned up to provide the crushers working load, 40,000 pounds in FIG. 4, whereupon the springs 37 are compressed an initial amount, all as illustrated by point A on the graph. Thereafter the load and the length of the springs 37 fluctuate between the points A and B on the graph during normal crushing operation, the load at the latter point being 80,000 pounds. In the event uncrushable material enters the rolls 18 and 23, the load increases beyond point B and compresses the springs 37 still further until the material has passed, whereupon the load and the length of the springs 37 return to the range between points A and B. If the uncrushable material is so large that the load is increased beyond point C of the graph, approximately 160,000 pounds, then the shear washer 42 are designed to fracture and relieve all pressure on the movable roll 23. The shear washers 42 are replaced simply by backing off the snub bolts 44, pushing the movable roll 23 and the accumulators 30 back to their original positions, installing new shear washers 42, and finally retightening the snub bolts 44. FIG. 5 illustrates a typical relationship of length versus diameter and load in the case of a spring 37 of the same material 6 inches in both length and diameter. From FIG. 5 it is evident that the springs 37 must be free to expand diametrically within their housing 33, whence the latter must spacedly encompass the former as indicated in FIG. 1. Generally speaking, a 4 inch difference between the two diameters concerned has been satisfactory. Other materials could be used, so long as they have sufficient spring rate and memory, and would have different hysteresis relationships from those shown as typical in FIGS. 4 and 5.

In order to adjust the spacing of the rolls l8 and 23, the snub bolts 44, after releasing the lock screws 45, are backed off and the accumulators 30 moved away from the bearing blocks 22. The shim packs 26a and 26b are equally adjusted on each side of the crusher until the proper roll spacing is achieved. In no event should additional shims be installed which cause insufficient clearance between the posts 14 and the shear heads 39; otherwise overload protection will be lost. The snub bolts 44 are turned up with a large wrench to force the accumulators 30 against the shim packs 26b and then further tightened until all the parts are in initial compression as indicated by point A in FIG. 4. Finally,'t'he set screws 45 are turned in to lock the bolts 44. Note that, as in thePollitz patent referred to, it is unnecessary actually to compress the nylon springs 37 in the sense that it is necessary to do so in the case of typical coil spring assemblies. Instead, the springs 37 are effective immediately upon tightening of the snub bolts 44. It is also important that the snub bolts 44 beretightened at regular intervals during operation of the crusher; loose bolts 44 will cause hammering on the shear washers 42 and their premature failure. Each accumulator 30 is readily removable as a unit for repair or replacement simply by backing off its snub bolt 44 and removing appropriate ones of the ears 34, whereupon it can be lifted out from between the slide bars 11 and 13.

Different crushers of course require different sizes of spring 37 to accommodate greater or lesser crushing loads depending upon whether the crusher is large or small. To accomplish this the length of the springs 37 is varied, longer lengths being used for the larger crushers and shorter lengths for the smaller. The various lengths of the springs 37 are accommodated by adjusting the length of the spacers so that the-same lengths of the housing 33 and snub bolts 44 can be used in each case. Likewise, overload protection provided by the shear washer 42 is altered by varying their thickness in order to accommodate the requirements of dif ferent sized crushers. While as shown and described each accumulator 30 employs but a single housing 33 and spring 37, there is no reason why a pair of the same could not be used for each accumulator if appropriate under the circumstances, though this would require additional structure in order to provide for proper adjustment and overload release.

While the present invention has been described in terms of a particular embodiment, being the best mode known of carrying out the invention, it is not limited to that embodiment alone. Instead, the following claims are to be read as encompassing all modifications and adaptations of the invention falling within its spirit and scope.

I claim:

1. In a roll type crusher having a frame and a pair of spaced crushing rolls journaled at each of their axial ends for rotation on the frame adapted to crush material therebetween by rotation of the rolls with respect to each other, at least one of the rolls being movable with respect to the other in order to adjust the spacing therebetween, the improvement in combination therewith of a pair of mechanical accumulators for substantially maintaining a predetermined spacing between the rolls during their crushing operation up to a predetermined load, the accumulators accomodating an overload by increasing the predetermined spacing until the overload has terminated and thereafter restoring the predetermined spacing, each of the accumulators comprising: a housing having opposite ends and a peripheral wall extending lengthwise of the housing; a block of material in the housing having opposite ends and a peripheral wall extending lengthwise of the block and the housing; the block ends being associated with respective ones of the housingends, and the peripheral wall of the block being in spaced relation to the periphal wall of the housing; the housing and block being disposed between a portion of the frame and one of the movable journals and operatively associated with both so that thrust between the rolls is communicated to the block ends and resisted by the body of the block lengthwise thereof, the block being constituted of a material effective to substantially maintain the predetermined roll spacingup to the predetermined load 'andupon a first overload to compress lengthwise and expand peripherally towards the housing wall in order to increase the predetermined roll spacing but upon termination of the first overload to expand lengthwise and contract peripherally effective to restore the predetermined roll spacing; and adjusting means operative between one of the block ends and one of the movable journals and frame portion to permit adjustment of the predetermined roll spacing independently of operation of the accumulator.

2. The apparatus of claim 1 including protective means disposed between one of the block ends and one of the movable journals and frame portion to receive thrust between the rolls, the protective means being effective to fracture and relieve all thrust from the rolls upon the block in the event of a second overload greater than the first overload.

3. The apparatus of claim 1 wherein one end of the housing and its associated end of the block is operatively associated with one of the movable journals, the other end of the block being operatively associated with the frame portion, so that thrust between the rolls is communicated to the one housing end and its associated block end and to the other block end.

4. The apparatus of claim 3 including first and second spaced members and a hollow cylinder therebetween constituting the housing, the first member being rigidly secured to and closing a first end of the cylinder and operatively associated with the movable journal to receive thrust between the rolls, the second end of the cylinder extending through the second member and being rigidly secured thereto, the block being a solid cylinder of said material having first and second ends operatively associated with the first member and the frame portion respectively.

5. The apparatus of claim 4 wherein the axis of the cylinder coincides with a line of thrust through the frame portion and intersecting the axis of the movable roll; and including a shear head in the second end of the cylinder and operatively disposed between the second block end and the frame portion, the adjusting means being operatively disposed between the shear head and the frame portion, the shear head and adjusting means together communicating thrust between the rolls to the second block end, and including shear means operative between the shear head and the adjusting means to relieve all thrust from the rolls upon the block in the event of a second overload greater than the first overload.

6. The apparatus of claim wherein the adjusting means includes cylindrical screw means threaded through the frame portion, the screw means being axially aligned with the cylinder, one end of the screw means carrying the shear means and releasably engaging the shear head, the other end of the screw means providing for rotation thereof, rotation of the screw means in one direction urging the shear means into engagement with the shear head and urging the members and cylinder toward the movable journal.

7. The apparatus of claim 6 wherein the members support the cylinder upon the frame, the members being slideable thereon between the movable journal and the frame portion upon rotation of the screw means in the otherdirection to disengage the shear head and shear means.

8. The apparatus of claim 7 wherein the members include means releasably mounting the members upon the frame, the members, cylinder and shear head being removable as a unit from the crusher upon release of the mounting means and rotation of the screw means to disengage the shear head and the shear means. 

1. In a roll type crusher having a frame and a pair of spaced crushing rolls journaled at each of their axial ends for rotation on the frame adapted to crush material therebetween by rotation of the rolls with respect to each other, at least one of the rolls being movable with respect to the other in order to adjust the spacing therebetween, the improvement in combination therewith of a pair of mechanical accumulators for substantially maintaining a predetermined spacing between the rolls during their crushing operation up to a predetermined load, the accumulators accomodating an overload by increasing the predetermined spacing until the overload has terminated and thereafter restoring the predetermined spacing, each of the accumulators comprising: a housing having opposite ends and a peripheral wall extending lengthwise of the housing; a block of material in the housing having opposite ends and a peripheral wall extending lengthwise of the block and the housing; the block ends being associated with respective ones of the housing ends, and the peripheral wall of the block being in spaced relation to the periphal wall of the housing; the housing and block being disposed between a portion of the frame and one of the movable journals and operatively associated with both so that thrust between the rolls is communicated to the block ends and resisted by the body of the block lengthwise thereof, the block being constituted of a material effective to substantially maintain the predetermined roll spacing up to the predetermined load and upon a fiRst overload to compress lengthwise and expand peripherally towards the housing wall in order to increase the predetermined roll spacing but upon termination of the first overload to expand lengthwise and contract peripherally effective to restore the predetermined roll spacing; and adjusting means operative between one of the block ends and one of the movable journals and frame portion to permit adjustment of the predetermined roll spacing independently of operation of the accumulator.
 2. The apparatus of claim 1 including protective means disposed between one of the block ends and one of the movable journals and frame portion to receive thrust between the rolls, the protective means being effective to fracture and relieve all thrust from the rolls upon the block in the event of a second overload greater than the first overload.
 3. The apparatus of claim 1 wherein one end of the housing and its associated end of the block is operatively associated with one of the movable journals, the other end of the block being operatively associated with the frame portion, so that thrust between the rolls is communicated to the one housing end and its associated block end and to the other block end.
 4. The apparatus of claim 3 including first and second spaced members and a hollow cylinder therebetween constituting the housing, the first member being rigidly secured to and closing a first end of the cylinder and operatively associated with the movable journal to receive thrust between the rolls, the second end of the cylinder extending through the second member and being rigidly secured thereto, the block being a solid cylinder of said material having first and second ends operatively associated with the first member and the frame portion respectively.
 5. The apparatus of claim 4 wherein the axis of the cylinder coincides with a line of thrust through the frame portion and intersecting the axis of the movable roll; and including a shear head in the second end of the cylinder and operatively disposed between the second block end and the frame portion, the adjusting means being operatively disposed between the shear head and the frame portion, the shear head and adjusting means together communicating thrust between the rolls to the second block end, and including shear means operative between the shear head and the adjusting means to relieve all thrust from the rolls upon the block in the event of a second overload greater than the first overload.
 6. The apparatus of claim 5 wherein the adjusting means includes cylindrical screw means threaded through the frame portion, the screw means being axially aligned with the cylinder, one end of the screw means carrying the shear means and releasably engaging the shear head, the other end of the screw means providing for rotation thereof, rotation of the screw means in one direction urging the shear means into engagement with the shear head and urging the members and cylinder toward the movable journal.
 7. The apparatus of claim 6 wherein the members support the cylinder upon the frame, the members being slideable thereon between the movable journal and the frame portion upon rotation of the screw means in the other direction to disengage the shear head and shear means.
 8. The apparatus of claim 7 wherein the members include means releasably mounting the members upon the frame, the members, cylinder and shear head being removable as a unit from the crusher upon release of the mounting means and rotation of the screw means to disengage the shear head and the shear means. 